CODEWITHSUNDEEP
c#vb.netlinqentity-framework
Chris Hippo
Chris Hippo

Reputation: 43

Creating an object with linq and EF without defining its fields

I have a simple method used to get a customer from the database by customerId:

Public Function GetCustomer(ByVal id As Long) As Customer

        Using ctx As New MyEntities
            Dim e = (From c In ctx.customers
                    Join bp In ctx.billingpoints
                    On c.customerId Equals bp.customerId
                    Select New Customer With {
                        .customerId = c.customerId
                        .billingPoint = New BillingPoint With{
                                            .customerId = bp.customerId
                                            .billingPointId = bp.billingPointId
                                            'tons of more fields   
                                        }
                        'tons of more fields
                           })
        Return e
    End Using
End Function

This method returns a Customer object defined like this:

Public Class Customer
    Public Property customerId As Long
    Public Property billingPoint As BillingPoint
    'many more fields
End Class

As you can see this looks horrible with all the properties being set. Is there any more effective way of doing this?

Upvotes: 0

Views: 71

Answers (3)

Jonas Høgh
Jonas Høgh

Reputation: 10874

I assume you're asking because your object model does not contain an explicitly mapped relation property of type BillingPoint on the customer object, but only an implicit relationship between the two entities via customerId property on BillingPoint.

If you want to keep your model like this, which can be valid in many cases, you could consider mapping the query result to a CustomerDTO type. This can be done automatically using AutoMapper and its Queryable extensions:

https://github.com/AutoMapper/AutoMapper/wiki/Queryable-Extensions

Upvotes: 1

Kjartan
Kjartan

Reputation: 19101

Quick idea: Not sure if this will work but you might be able to add a Constructor in Customer which takes the objects from your entities results as input parameters. Then you could do something like;:

Select New Customer(c, bc)

You might have to get the result using As Enumerable to achieve this though, which means you will need to take care not to fetch and iterate over more results than you need to.

Upvotes: 0

Rami Sakr
Rami Sakr

Reputation: 372

You can use the classes generated already by Entity framework, without having the need of recreating your types with properties, unless you need a specific type of model, then you'll have to do the mapping manually, or write a generic extension that maps the columns to specific properties by "Name"

Upvotes: 0

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